Gary Baldwin has a very particular set of skills. Firstly, he is a highly experienced crash investigator for the police. Secondly, he is an ex-police motorcyclist who now runs the highly respected Rapid Training. And thirdly, he’s an ex-racer. So he’s fast, can teach and knows the most common ways we crash. Here’s his guide to staying sunny side up.

Filtering is fundamentally a safe thing to do if you do it right – and it is legal. Any form of overtaking has more risks involved than not doing it, but you go through all the crap of sitting on a bike in the cold and wet so you might as well make use of the advantages.

Speed at around 18mph looks about right for the conditions, but our rider would be wise to stop filtering before the junction. That’s when drivers can get erratic.

What’s the most common filtering crash?

In town atjunction, often down to usual ‘courtesy causes confusion’ scenario. So you’re filtering past a line of slow moving traffic but you don’t notice that one of the cars has left a gap so someone in a side road can pull out and turn right. Someone waves them out and the first thing you see is their wing. You have to remember that they genuinely can’t see you when they pull out.

So what’s the plan?

You need to look out for junctions because they’re the danger pinch point. You need to ask yourself ‘should I overtake a car past a junction, or would it be best to stick with the car I’m overtaking as I go past the junction?’ Almost certainly, it’s the latter. You only lose 20 yards of filtering.

And what about speed?

Filtering accidents are generally the result of an inappropriate speed differential, whether you’re filtering on the motorway or in town. You need to keep the difference between the cars and you as low as you reasonably can.

You mentioned speed. What’s a safe one?

Filtering is all about keeping things sensible, and it’s not the speed number itself that matters, it’s the differential. You can’t say it’s safe to filter at 20mph or 50mph – it’s all about the difference. Personally I’m happy doing 10-15mph more than the traffic filtering in slow motorway traffic, and a lot less than that in town.

Has that car pulled wide to let our rider through, or is it mid weave and about to close the gap? Thanks to the artic filling the lane, it all looks rather too close for comfort

Are there any filtering crashes not involving speed?

Yes, occasionally we see them where a bike has filtered round the front of a lorry at a junction and is sitting right in front of it or by the nearside. You could hide a brass band in the blindspots at the front of a lorry – unless you’ve got eye contact with the driver, don’t go there. He’s got seven mirrors – by the time he’s checked them all, the situation in the first one has changed.

Are filtering accidents common on motorways and dual carriageways?

They’re less common than in towns, but they tend to have much worse outcomes because the speeds are higher. I’ve got some video of a bloke on the M4 where the traffic is doing 10-20mph and he comes past at what we calculated was 92mph between lanes two and three. You can see where that’s going to end, and it wasn’t pretty. When a driver looked in his mirror there was nothing there, so he changed lanes...

What’s the upper filtering limit?

Everyone has a point where they don’t want to filter any more. It depends on the conditions, but I tend think that at 50-60mph I’m happy to stop filtering and sit in the traffic. Some people are in much more of a hurry than that, which I’m not criticising provided the speed differential is sensible. So if you’re happy filtering at 70mph, don’t do it past cars doing 40.

Where do I filter on motorways? Between lane 2 and 3?

I think that between lanes two and three is the best place because my experience is there are fewer lane changes, though I’ve got no formal evidence of that. Also there’s usually more space because there are fewer lorries. I don’t like going between the off-side and the barrier because there’s a vibroline there that I don’t want to ride over and because of all the dead badgers, wing mirrors etc. Unless it’s absolutely stationary and you’re doing 10mph, that’s a no-no.

Anything else to bear in mind?

At night it’s worse because as a driver when you look in your mirror, what do you see? A load of lights. You just put your indicator on, you know there’s a gap and over you go. Or you don’t indicate – lots of drivers don’t. Another thing to consider is that at higher speeds, the cars can change lane faster.

What about other riders?

I always like to be following someone else because he’s the wake-up call for all the drivers ahead.

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